超声提取辅助浸入式固相微萃取-气相色谱/质谱技术快速检测土壤中的有机氯农药残留

建立了超声提取辅助浸入式固相微萃取-气相色谱/质谱(DI-SPME-GC/MS)方法快速检测土壤中有机氯农残的新方法.该方法可实现分离、富集和进样一体化,减少样品前处理步骤.实验优化了DI-SPME的萃取条件、超声提取条件及GC/MS仪器参数.在优化条件下,9种OCPs在实验浓度范围(20—500 ng·g-1)内,线性关系良好,R2为0.9899—0.9987,方法检出限在0.67—1.76 ng·g-1,加标回收率在80.2%—117.1%,相对标准偏差(n=6)为10.0%—12.0%.结果表明该方法是一种简便快速、绿色环保的分析土壤中OCPs农残的方法.     

巢湖主要湖口水体和表层沉积物中有机氯农药的残留特征及风险评价

为了解巢湖湖口有机氯农药的污染状况,采集8个主要湖口的水体和沉积物样品,水样采用C18固相富集,沉积物用加速溶剂萃取仪提取后,萃取液浓缩、净化后,微量浓缩,用气相色谱-质谱联用仪分析测定21种有机氯农药.结果表明,研究区水体和表层沉积物中OCPs总量范围分别为40.1—87.7 ng·L~(-1)和11—26.3 ng·g~(-1),HCHs和DDTs为主要污染物,约占79.9%和65.1%.水体中OCPs含量从高到低依次为:南淝河十五里河双桥河派河裕溪河杭埠河大柘皋河小柘皋河;表层沉积物中OCPs含量从高到低依次为:十五里河双桥河南淝河裕溪河派河大柘皋河杭埠河小柘皋河.OCPs污染水平表现为城市污染控制型河流高于水土保持和面源污染控制型河流.根据组成物质成分比例关系进行源解析,发现水体和沉积物中HCHs和DDTs主要来自于早期农药蓄积残留,且降解环境以好氧为主.与国内其他湖泊对比,巢湖OCPs污染处于中等偏低水平.水体中HCHs、DDTs和六氯苯均未超过地表水环境质量标准,但表层沉积物中有机氯农药存在一定的生态风险.     

液液萃取-固相萃取-气质联用测定指甲中的多溴联苯醚与多氯联苯

利用液液萃取(LLE)与固相萃取法(SPE)提取和净化人体指甲中的多溴联苯醚(PBDEs)和多氯联苯(PCBs),经浓硫酸除脂后,利用气相色谱-质谱联用仪(GC-MS)测定PBDEs和PCBs.对提取溶剂比例、净化柱类型(复合硅胶柱与固相萃取柱)、固相萃取条件(洗脱溶剂及体积)以及脂肪的去除方法进行了优化,加标回收率较前人基础上均有明显提高.加标回收试验结果显示,PBDEs和PCBs平均基质加标回收率分别为90%—110%和71%—102%,空白加标回收率分别为70%—110%和60%—100%之间,仪器检出限(IDL)分别为0.034—0.120μg·L~(-1)和0.032—0.392μg·L~(-1).本方法快速、简单、高效,能够满足指甲中PBDEs和PCBs的分析.同时本研究利用该方法对电子垃圾拆解地区居民的指甲样品进行测定,PBDEs和PCBs平均浓度分别为623 ng·g~(-1)和148 ng·g~(-1),BDE(-154、-153、-183、-209)和PCB(-8、-28、-52、-66、-101、-77、-118、-153、-187)在所有样品中均检出,女性指甲中PBDEs与PCBs的浓度普遍高于男性.     

海洋沉积物中甾醇类物质的气相色谱/质谱方法分析

应用超声提取技术,结合硅胶-中性氧化铝柱层析净化分离,BSTFA+1%TMCS衍生,及气相色谱-质谱定性定量技术,建立了海洋表层沉积物中8种甾醇类化合物的定量分析方法.实验采用正交实验优化了提取过程中提取剂种类、试剂体积和超声时间,同时对比并优化了柱层析淋洗液的配比、用量以及衍生剂的用量.结果表明,50 mL二氯甲烷/甲醇(V/V,2∶1),超声40 min,超声3次,总甾醇的萃取率可达99.6%;3 g硅胶+2 g中性氧化铝层析,35 mL二氯甲烷/甲醇(V/V,9∶1)淋洗净化回收最佳;8种甾醇在0—848μg.L-1范围内有良好的线性关系;方法检测限为1.2—2.4 ng.g-1.在3种浓度水平0.05、0.1和1.0μg.g-1下,其平均回收率为76.2%—100.9%,相对标准偏差为1.0%—10.3%.应用本方法检测大连湾的3个沉积物样品,8种甾醇的含量在0.079—6.833μg.g-1范围内.本方法的灵敏度高、准确度好,适合用于沉积物样品中甾醇物质的检测要求.     

利用氧化铝-改性硅胶联柱分离测定水中多氯联苯

本文介绍一种多氯联苯(PCBs)与农药的分离和气相色谱分析PCBs新方法.富集浓缩后的样品首先经浓硫酸酸洗.排除大多数干扰PCBs测定的有机化合物,然后利用氧化铝-硅胶(Ag~+)联柱实现了PCBs和干扰其测定的农药的完全分离,应用毛细管气相色谱分析测试了水样中多氯联苯多种同系物、同分异构体的含量.其方法的回收率在79—88%之间.     

清远某电子垃圾拆解区河流底泥中重金属和多氯联苯的复合污染

通过采集清远某电子垃圾拆解区6个点位沉积物样品,测定底泥的p H、有机质、4种阴离子、重金属和多氯联苯的含量,研究电子垃圾对附近河流产生的影响及危害.采用原子吸收、离子色谱、气相色谱质谱联用(GC/MS)分析底泥中重金属、阴离子、PCBs(Polychlorinated biphenyls)的含量.结果显示,排污两点表层底泥的有机质含量达到11.73%和11.34%;4种阴离子含量为:SO2-4Cl-F-NO-3,SO2-4和Cl-的浓度在排污口表层含量高达320 mg·kg-1和60 mg·kg-1,阴离子含量随深度的增加而降低;排污口表层底泥的重金属Cd、Ni、Pb、Cu、Zn、Cr的含量最高分别能达50.87、967.89、5571.75、15673.09、10075.26、2253.86 mg·kg-1,超出《国家土壤环境质量标准》(GB15618—1995)三级标准;沉积物中PCBs含量在0.36—3.160μg·g-1,以三—五氯为主,约占总量的70%,生态风险大于50%,毒性风险较高.Cd和PCBs是最主要的生态风险因子,在排污口两点除Cd和PCBs外,Pb和Cu的生态风险也很强,RI值高达5000以上,具有极强的生态危害性.     

城市污水污泥中PCBs的分析及其QA/QC研究

采用正己烷/丙酮混合萃取剂索氏提取污泥,浓硫酸洗涤和硅胶层析柱净化分离出纯净的PCBs,以毛细管GC-ECD和内标法对PCBs定量,并进行了QA/QC研究.以实际城市污水污泥作为加标基质,方法的检测限为0·92—2·82ng·g-1(干重),19种PCBs同族体的回收率为54·2—140·6%,相对标准偏差为6·5—15·3%,满足US EPA对PCBs回收率的要求.经过3次平行分析,城市污水污泥中含有12种PCBs,PCBs总量的平均值为115·73ng·g-1(干重),相对标准偏差为9·57%.     

卧龙巴郎山地区夏、冬两季土壤中有机氯农药和低氯代多氯联苯的海拔高度分布

利用同位素稀释质谱法测定了卧龙高海拔地区土壤中有机氯农药(OCPs)和低氯代多氯联苯(PCBs)的含量.海拔高度2800 m以上,土壤中HCHs和DDTs平均含量冬季(0.517和0.556 ng·g-1dw)高于夏季(0.293和0.323 ng·g-1dw).夏、冬两季的土壤中PCB28和PCB52含量浓度水平相近.以土壤干重表示的OCPs和低氯代PCBs含量随海拔升高而降低,而用有机碳归一化表示的含量随海拔升高而增加,证明了在卧龙高海拔地区存在着POPs的辛醇-空气分配系数与冷凝结效应相结合的富集现象.     

环境介质中三唑磷农药残留分析方法

正环境介质中三唑磷(TAP)残留量低以及提取物组分过于复杂,样品需要经过富集和净化等前处理过程才能进行液相或气相检测.液-液萃取-气相色谱分析小麦地中土壤和秸秆中TAP含量分别达到0.973和1.865 mg·kg-1,气相色谱分析柑桔土水中TAP浓度在1—10μg·L-1[1],液-液微萃取和高效液相色谱分析水和果汁中的TAP残留浓度也取得较高的灵敏度[2].与液-液萃取相比,固相萃取(SPE)技术具有操作简便快速、有机溶剂用量少,且能去除一些杂质等优点.本     

渤海湾南排河海域脉红螺中多氯联苯的污染特征

本文利用气相色谱-质谱/质谱测定了渤海湾南排河海域野生脉红螺肌肉组织中多氯联苯(PCBs)的含量,并对其污染特征进行讨论.结果表明:(1)肌肉中多氯联苯(∑PCBs)总浓度在8.40—10.06 ng.g-1(lw,以脂肪质量计)之间,其中PCB-114含量最高(0.74—1.06 ng.g-1(lw));(2)五氯联苯和六氯联苯为主要检出组分,占∑PCBs的43.7%—84.8%;(3)雌性脉红螺个体中PCBs的平均浓度略高于雄性及性畸变脉红螺中PCBs的平均浓度,分别为(10.06±0.89)ng.g-1(lw)、(8.40±0.63)ng.g-1(lw)和(8.51±0.67)ng.g-1(lw),但性别间无显著性差异.     

On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

刍议医院资产管理的现状及其对策

医院的固定资产和流动资产是医院赖以生存和发展的基础,是一项非经营性国有资产．目前公立医院固定资产、流动资产管理现状不容乐观,针对这种状况,首先分析问题形成的原因,然后提出管理的措施或建议,从而使资产管理工作规范化、制度化、科学化,使有限的卫生资源发挥出最大的社会效益和经济效益．参3．     

豪猪消化系统的解剖研究

为了了解豪猪的消化生理,为豪猪的人工饲养技术研究提供基础依据,以达到高效饲养豪猪的目的,笔者对豪猪的消化器官进行了系统解剖研究.结果表明:豪猪的胃为单室胃.盲肠很发达,这与其能够消化植物纤维有关.豪猪肝脏很发达,其重量为402 g,是其体重的4.59%,肝脏分叶多而明显.     

Adjusting the economy to the new energy realities of the second half of the age of oil

Our research indicates that, due to the depletion of conventional, and hence cheap, crude oil supplies (i.e. peak oil), increasing the supply of oil in the future would require exploiting lower quality resources (i.e. expensive), and thus will most likely occur only at high prices. This situation creates a system of feedbacks where economic growth, which requires more oil, would require high oil prices that will undermine that economic growth. We conclude that the economic growth of the past 40 years is unlikely to continue unless there is some remarkable change in how we manage our economy.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

The impact of the Jonglei Canal on the economy of the local people

The idea of saving the water lost in the ‘Sudd’ swamp through evaporation was conceived by Egypt and Sudan for their own interests, but not for those of the Nilotic peoples living in the flood plain. Concern for the local development was only taken into consideration after the 1974 Juba riots, when three people were killed and 200 arrested. The canal has caused displacement of people from their settlements and is blocking the seasonal movement of livestock and wildlife. Conflict may arise over the use of land for grazing or irrigation. The Nilotics are concerned about the possible negative environmental impact, and the loss of their cultural identity. They maintain that Egypt should pay them monetary compensation for the disruption that the canal has caused to their livelihood.

This paper assesses the impact that the Jonglei canal project will have on the economy of the Nilotics; traces the historical development of the project; outlines the social, political and economic organization of the Nilotics; and assesses the impact the project will have on the local population. The paper concludes by casting doubt on the benefits the canal will bring to the Nilotics.     

Mining of the forest and the time path of the price of timber

The paper analyzes the effect of transportation (site specific) costs and the effect of mining (depletion) of the forest on the time path of the price and of the net price of timber in two forestry models. The models differ in that one has zero costs and the other has positive costs. The analyses yield the standard mining theory results for certain cases. They also yield extentions of these results for cases with growth of the harvested trees and/or regeneration on the harvested land. The paper concludes, as one would expect, that the theory of the mine is useful in analyzing the time path of the price of timber.     

三峡库区消落带土壤中铅污染调查

报道了三峡库区长江干流及小江支流消落带土壤中重金属铅含量背景值的调查结果。结果表明，目前土壤未被重金属铅污染。     

浅谈校园网ARP欺骗攻击与防御

ARP欺骗木马病毒是校园网络中经常出现的病毒攻击形式．基于ARP协议的概念和工作原理,并通过分析ARP欺骗的工作原理,提出了几种可行的解决ARP欺骗攻击的实用方法,以达到防范并解决ARP欺骗的目的．参5．